1. Technical Field of the Invention
This invention relates to radio telecommunication systems and, more particularly, to a system and method for paging Mobile Stations (MSs) that minimizes the signaling load between Mobile Switching Centers (MSCs) and Base Stations (BSs) in a radio telecommunications network.
2. Description of Related Art
When a call for a particular MS is received in a typical cellular radio telecommunications network, the MSC receiving the call interrogates the serving MSC where the MS was last known to be operating for a routing number. The serving MSC then sends a page message to each BS in its service area that is to page the MS. In a typical paging scenario, the MS is first paged in a xe2x80x9clocation areaxe2x80x9d which is a plurality of cells surrounding the last known location of the MS. If the MS is not found in the location area, the search is expanded to a xe2x80x9clocation area groupxe2x80x9d which is a plurality of location areas. Finally, if the MS is not found there, the MS is paged throughout the entire xe2x80x9cservice areaxe2x80x9d of the network. Each level of paging requires a plurality of page messages to be generated and sent to the plurality of BSs that are to page the MS. Clearly, as the search broadens to the location area group or the service area, a large number of page messages are typically generated. For example, when paging the service area of a typical exchange, 400 or more page messages may be required. This can be a heavy burden on the processing capacity of the MSC and on the signaling capacity of the network. This signaling burden becomes even more of a problem when it is considered that, at any given moment, the network may be paging for a plurality of MSs.
In order to overcome the disadvantage of existing solutions, it would be advantageous to have an improved system and method for transmitting page messages from MSCs to BSs in a cellular network that eliminates the heavy signaling burden currently experienced. The present invention provides such a system and method.
In one aspect, the present invention is a method of paging mobile stations in a cellular telecommunications network having a Mobile Switching Center (MSC), a plurality of Base Stations (BSs) in a network service area, and an Internet Protocol (IP) network connecting the BSs to the MSC. The method includes the steps of assigning a common IP broadcast address to all of the BSs in the service area, broadcasting an IP page message to the common IP broadcast address, and dedicating at least one User Datagram Protocol (UDP) port in each of the BSs to receive the page message from the MSC. The step of dedicating at least one UDP port may include dedicating a first UDP port to receive page messages directed to a location area with which the BS is associated, dedicating a second UDP port to receive page messages directed to a location area group with which the BS is associated, and dedicating a third UDP port to receive page messages directed to the network service area.
In another aspect, the present invention is a system for paging mobile stations in a cellular telecommunications network having an MSC serving a network service area and a plurality of BSs having a common IP broadcast address. The system includes an IP network connecting the BSs to the MSC, means in the MSC for broadcasting an IP page message to the common IP broadcast address, and at least one UDP port in each of the BSs dedicated to receiving the page message from the MSC. A first UDP port may be dedicated to receiving page messages directed to a location area with which the BS is associated. A second UDP port may be dedicated to receiving page messages directed to a location area group with which the BS is associated. A third UDP port may be dedicated to receiving page messages directed to the network service area.
In yet another aspect, the present invention is an IP Base Station (BS) in a cellular telecommunications network having an MSC serving a network service area. The BS includes a first UDP port that receives only page messages from the MSC directed to a location area with which the BS is associated, a second UDP port that receives only page messages from the MSC directed to a location area group with which the BS is associated, and a third UDP port that receives only page messages from the MSC directed to the network service area. The BS also includes means for paging a mobile station in response to receiving a page message from the MSC through the first, second, or third UDP port.